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ec779715bd Shrink theme backgrounds without touching resolution (#7266 )

* Re-encode over-encoded theme backgrounds

Several backgrounds shipped at quality 95-100, which buys nothing visible
on a wallpaper but costs 20 MB. Re-encode those at quality 85, leaving
resolution untouched -- every file keeps its original pixel dimensions.

Only files stored above quality 90 are touched, and only when the result
saves at least 15% and stays above 38 dB PSNR against the original. The
34 backgrounds already stored at quality 85 or below are left alone
rather than pushed through another lossy generation for a few hundred KB.
osaka-jade/2-shaded-entrance is skipped for that reason: nothing clears
both bars. ristretto/2-coffee-beans is re-encoded at 90 instead of 85,
where 85 fell below the PSNR floor.

Theme backgrounds drop from 107 MB to 87 MB.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

* Store nord's night-hawks background as a palette PNG

The file uses only 8 distinct colors but was saved as truecolor RGB,
costing 1.8 MB for an image an indexed palette stores in half the space.
Converting to a palette PNG is lossless: same dimensions, and zero pixels
differ from the original.

1782 KB -> 909 KB.

The other palette-eligible PNGs are already indexed, and re-compressing
them with ImageMagick only makes them bigger, so they are left alone.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

* Recompress theme PNGs losslessly with oxipng

Every background PNG was left at its authoring tool's default deflate
settings. Running oxipng over them re-packs the same pixels: all 31 files
decode bit-for-bit identically (AE=0) at unchanged resolution, for 981 KB.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

* Store photographic backgrounds as JPEG instead of PNG

Four backgrounds were shipped as PNG despite being photographs and
painterly illustrations, where lossless coding buys nothing the eye can
see. Re-encoding them at the same q85 used by the other backgrounds keeps
every pixel dimension and stays above 40 dB PSNR, for 3.3 MB.

The remaining PNGs stay PNG: JPEG is larger for the dot patterns and the
flat-shaded pieces, and 0-launch.png genuinely uses its alpha channel.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

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Co-authored-by: David Heinemeier Hansson <david@hey.com>
Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

2026-08-18 18:29:23 +02:00